Telegraph switching system



June 20, 1950 E. J. AGNEw 2,511,832

TELgGRAPx-x swI'rcHING sYsma Filed Jan. 16, 1945 5 Sheets-Sheet 1 `[une 20, 1950 Filed Jan. 16, 1945 E. J. AGNEW TELEGRAPH SWITCHING SYSTEM 5 Sheets-Sheet 2 FIG. 2 wT-m PULL. TAPE INVENTOR E. J. AGN EW ATTORNEY PREEMFTI June 20, 1950 E. J. AGNEw TELEGRAPH SWITCHING SYSTEM Filed Jan. 16, 1945 5 Sheets-Sheet 3 1 INVENTOR E. J. AGN Ew BY W ATTORNEY FIG. 3

June 20, 1950 E. J. AGNEw TELEGRAPH SWITCHING SYSTEM 5 Sheets-Sheet 4 Filed Jan. 16. 1945 JOKPZOO DPD( INVENTOR E'. J AGNEW ATTORNEY mmulum NDF E. J. AGNEW TELEGRAPH SWITCHING SYSTEM June 20, 1950 5 Sheets-Sheet 5 Filed Jan. 16, 1945 TIE @Ing mdz N umask N hummm...

.Pm-D KDE Emma-mm INVENToR E J AGNEw Sama x ATTORNEY Patented June 20, 1950 UNITED- VSTA'IyE-S PATENT OFFICE "TELEGRAPH SWITCHING SYSTEM Edward J. Agnew, Brooklyn, N.` Y., assignorjto The Western Union Telegraph Company, New York, N. Y., a'corporation of New York Y Application January 16, 1945, vSerial No. 573,050

13 Claims.

, 1 This invention relates tomtelegraphswitching or exchange systems and, more particularly, to reperforator types of telegraph switching systems.

In general, telegraph switching systems of this type provide. means whereby messages received over incoming lines or circuits may be stored and reftransmitted over selected outgoing lines or circuits. The receiving lines or circuits lterminate in and control mechanisms known Y as printer-perforators which perforate and print on a tape characters representing the received code combinations. Each receiving rprinterperforator has associated therewith a so-called intra-oce tape transmitter which is controlled in accordance with the signals stored in thetape prepared by the printer-perforator. The intraofce tape `transmitter has an associated cord circuit and plug whereby it may be selectively connected through jacks to any one of a plurality of so-called intra-office perforating mechanisms which preparev a second tape to controlan as-- sociated line or circuit transmitter. Each outgoing circuit has associated therewith a line tape transmitter adapted to transmit to the sending circuit code combinations representative of the perforations in its control tape. In this manner a message received over any incoming line or circuit is stored in a printed and perforated tape, transmitted intra-office to the desired outgoing terminal, again stored in a perforated tape, and then transmitted over the proper outgoing circuit. Such systems vare sometimes called double storage reperforator switching systems.

It is one of the features ofthe present invention to provide means operable in conjunction with a system of the above general type whereby certain messages, hereinafter referred to as X messages, may receive special handling and thereby be transmitted to an outgoing lineY out of turn or ahead of messages which may be waiting for transmission to such a line at the time an X message is received.m

Another feature of the invention resides in the provision of means for normally transmitting an"X'message`to an outgoing circuit only at the end of transmission of a message which may he in progress of transmissionat the time the' X message transmitter is connected to the circuit.

In this connection, another feature ofthe` invention resides in the provision of means Whereby on the operation of a control, the X message Will be transmitted at the time the X message transmitter is connected to the outgoing circuit Withoutk waitingfor the end of a message which may be then in progress of transmission.

In4 connection4 with the above, another feature oi,.the inventionresides in a character reading devicein the` ,Xj cord circuit ,which reads the signals being transmitted over anoutgoing circuit and connects thefX? message tapeutransmitter thereto to transmit thereover only after the detection` of an end-of-message signal following the message which may be in theprocess of transmission from the regularline transmitter. In other words, the system of the present invention provideswacharacter reading device which is operative only when it is desired to transmit an message over an outgoing circuit. ,With this arrangement a character reading ydevice for each outgoing circuit is not required,J and since the number of X message transmitters is greatly less than the number of outgoing circuits, a considerable saving in equipment atan exchange of the above `type is possible as compared to earlier systems where each outgoing circuit .had an associated character readingndevice. i

. AA further feature of the present invention residesfin the provision of means for the X cord circuit to detect and indicate the type of outgoing circuitto which the X tape transmitter may be connected whereby among other ythings the proper Vpolarity is applied to the connected circuit when the X transmitter is locked under tight tape conditions.

AThe above mentioned andother features of the invention will b e more apparent hereinafter when taken in conjunction with the accompanying drawings, in the latter4 of which:

- Fig.- 1 is a diagrammatic representation ofa switching system embodying thefeatures of the present invention;

. Figs. 2 to 5 are `detailed circuit drawings of the part of the systemshown in Fig. 1 relating to the present invention; and

`Eig. 6 `shows how Figs. 2 to 5 may be arranged to produce a complete circuit drawing.

Referring Vrst toFig. 1, which is a diagrammatic representation of a system of the type to which the present invention may be applied, Ll to L4 represent incoming lines Yor circuits over which code combinations,representing messages may be received. Each such circuit vterminates in aprinter-perforator Il which prepares a tape I2 in accordance with received signals. The tapes l2 have printed along one vedge characters representing thel code combinations and are perforated inanother section to represent, in accordance v with a predetermined arrangement,

with their associated equipment such as printer perforators I I, cords I4 and plugs I6 are arranged in groups and each such group Vconstitutes a switching position. These switching positions are hereinafter referred to as turrets and the various pieces of equipment ther-eat are identiiiied and referred to accordingly. The three jacks Il identified by the lettersV W, Y, Z in each oi' the two switching positions or turrets No. I

and 2 shown are connected in multiple to associated periorators I8 over intra-oiilce circuits I9.

l When a message is received over an incoming circuit, it is printed and perforated in the tape I2 and ,a turret operator noting the destination or the message, places the plug I6 in the appropriate jack at that turret, whereupon the 24. The X turret operator on observing a message in the tape 24 reads the address and inserts the plug 26 connected to the tape transmitter 2l associated with the tape into the proper X turret jack such as those indicated W, Y or Z.

Each X turret cord circuit associated with a plug 26 and tape transmitter 21 has included therein a reading device. If the X turret tape transmitter 2'1 is connected to a busy outgoing circuit, the reading device reads the characters message is transmitted intra-cnice and reperroratedV by a perforator I8 in another tape 2l. Each of the tapes 2| from the perforators I8 control associated so-called line transmitters 20 which in turn through appropriate distributors affect transmission of the message characters to sending circuits. In Fig. 1 the circuit to remote-oice W is assumed to -be over the A channel of a multiplex, that to remote oice Y over the B channel of a multiplex, and that to remote olice Z over a teleprinter circuit. Systems of the above general type are well known in the telegraph art and examples thereof may be found in Patent No. 2,279,295, issued April 14, 1942, te` W. B. Blanton.

In order to expedite the switching of messages intra-office, the intra-oilice circuits represented by the reference numeral I9A are arranged to operate a-t a considerably higher rate than that at which the incomingv and outgoing circuits normally operate. Accordingly, it sometimes happens that on a busy outgoing circuit a number of messages may be stored in a tape such as 2-I Vof-a line tape transmitter 2li-'with the messages stored insuch a tape in the order in which they are received over the incoming circuits. When an X" message is received at a switching center, it is highly desirable that such a message be transmitted-over an outgoing circuit without waiting for the transmission of messages which may be stored inthe tape such as 2|.

When these X messages are received on a printer-perforator, the turret operator is apprised of such a message and she inserts the associated plug I6 in a so-called X jack of which each turret has oneA or more. The X jacks of all the turrets extendv` to a so-called X turret and they may be connected thereto through line finder switches such as 22 which, in a manner well known, operates to connectl an X turret printer-perforator 23Y to the jack in which a plug such as I6 may be inserted. As,` shown in Fig. 1, there are two X turret printerperforators 23 and the line switches 22' operatev in such a manner that each time a plug I6 is inserted in an X jack, either one or the other ofv the printer-perforators 23 will be connected to such a. jack to eiect recording of the message in its associatedI printed andperforated tape of the message being transmitted and normally holds up transmission from the X turret tape transmitter 2 until an end-of-message signal is read whereupon transmission begins from the X Vturret transmitter regardless of the number of messages that may be stored in the tape 2| of the associated line transmitter 20. If there are no characters being transmitted over the associated sending circuit, the X turret tape transmitter is substantially immediately connected thereto to transmit the message stored in its associated tape 24. Although the X turret tape transmitter normally waits for the end-of-message signal to be transmitted before beginning transmission of the X message, the operation of a so-called pre-empt key permits the "X turret tape transmitter to be connected to a sending circuit at any time, such as in the middle of a message in the progress of being transmitted from the line transmitter. 20.

One multiplex channel mayA mark on negative potential and space on positive potential whereas another channel-may mark on positive and space on negative. It is assumed that the channels to oices W and Y spac'e and mark on different polarities and are identied as being channels A and B, respectively, of multiplex circuits. The X tape transmitter 21 is adapted to operate into either an A ychannel or a B channel of a multiplex, or into a teleprinter line, and means are provided to determine which type of line may be connected thereto. This is necessary since spacing battery (positive on an A- channel and negative on a B channel) must -be applied to the line when and if the X turret tape transmitter tape -lever is operated during transmission of a message therefrom. Ii connected to a teleprinter circuit, marking battery must be applied to thel line when the tape lever of the X turret tape transmitter is opened.

Let it be assumed that the line transmitter 20 associated' with the A channel of a multiplex circuitv extending to remote oflice W, is transmitting a message and that a number of other messages-are stored in its control tape 2l waiting to betransmitted in turn. Let it be further assumed that an X message is received at the X turret for transmission to remote oce W while the line tape transmitteris transmitting thereto. The X turret operator observing the destination of the message inthe tape 24 will insert the plug26 in the-X turret jack W. Since it is assumed that the sending circuit to remote oilce W is over an A channelA of a multiplex circuit'the assumed polarities of potential f for' such a channel will be marking negative through the coil of a relay 28, the number 1 contacts of the jack and plug, the right hand coil of another relay 29 and resistance 3| to ground. The iiow of current through this circuit is limited by resistance 3| to a value below that necessary to operaterelay 28 but is suicient to operate relay 29.

When the line transmitter is transmitting to the multiplex distributor 32, the tongues of the transmitter apply combinations of positive and negative potential through tongues and back contacts of relay 28 to the segments 1 to 5 of the multiplex transmitting ring. These combinations of potential are in accordance with the character over the pins in the tape transmitter 23 at any particular time. The plugging operation establishes leak circuits from the tongues of the line transmitter 20 through contacts VNos.4, 5, 6, 7 and 8 of the plug and jack and separate resistances 33 to the control gridsof a set of five vacuum tubes 34. The leak circuit from the fourth tongue of the tape transmitter 2.9 passes through the back contact and right hand Atongue of a relay 36 to the seventh conductor` ofv the cable 52 of jack W. Normally, the grids of vacuum tubes 34 have negative potential lapplied thereto from the right hand tongue and back contact of a relay 31, through the back'contact and outer tongue of relay 29 and resistanoesY 38, similar in Value to resistance 33.

When relay 29 operates in the manner set forth, the outer tongue thereof removes the normal negative potential from the grid circuits of Vacuum tubes 34 and applies a low-value p ositive potential thereto through the resistance 4G and individual resistances 38. Thus, circuits are established whereby the potentials on the grids of the individual vacuum tubes' 34 correspond to the positions of the tongues of the tape transmitter 20. For the assumed conditions, a grid of a vacuum tube 34 will be negative when its respective tongue of transmitter 20 contacts its marking bus bar and positive when its associated tongue contacts the spacingl bus bar. When the grid of a vacuum tube 34 is rendered positiva, plate current is permitted to flow through lthe tube and plate current is cut off when the grid is negative. In the individual plate circuits of the vacuum tubes 34 are the coils of ve socalled reading relays 39a to 39e. The other Side of the coils of relays 39 are connected topositive potential and, therefore, when a tube is passing plate current the associated relay` will be operated and will be unoperated when the tube is not passing current. Thus, the reading relays 39 are operated in Various combinations to represent each character as they are transmitted from the line tape transmitter 20.

A code combination wherein the rst, second, third and fifth impulses thereof are spacing and the fourth impulse marking represents a period and the stepping of such a character over the pins of the tape transmitter 2U establishes a circuit for the operation of a relay 4|. This circuitinay` be traced from positive potential through the coil of relay 4|, the back contact andvtongue of `a relay 42, the left hand tongue andfront contact of relay 31, the fthtongue and back -contact of a relay 43, the back contact and outer tongue of relay 39d, the outer tongue andfront contact of 39e, the back contact and outer tongue of relay 43, the outer tongue andfront contact of relay 39e, the back contact and fourth tongue of relay 43, the outer tongue and front contact Of relay 39h.. the backcontact and thirdfjtonsue ofrelay 43, the outer tongue and front contact of relay39a, the back contact and second tongue of relay 43, the outer tongue and back contact of a relay 44, the back contact and outer tongue of a relay 46, the .back contact and inner tongue of a relay 41 through the third tongue and back contact of relay 59 to ground.` The coil of relay 31 is in shunt relation with that part of the above described circuit extending from the front contact of the said relay and it will, therefore, be

renergized on completion of that part of the circuit and -its energization completes the rest of the said circuit including the coil of relay 4| whereby relay 4| is energized. Thus, when a period is stepped over the pins of the line tape transmitter 20, relay 4| will become energized.

, When the first period is stepped out of the line transmitter 2U all the tongues thereof contact the spacing bus bar whereupon positive potential will be applied to all the grids of vacuum tubes 34 so that all the relays 39 become operated. This condition establishes a circuit for the operation of relay 42, This circuit may be traced from positive potential through the coil of relay 4|, the front contact and tongue thereof, the coil of relay 42, and through a part of the abovedescribed circuit including the outer tongues and make-contacts of relays 33e, c, b and a, the second, third, fourth and sixth tongues of relay 43 and contacts of relays 44, y43 and 23 to ground.

If the next character following the first period in the line transmitter 20' is any other except a blank or a period, relays 4I and 42 will be released as the reading relays 39 are operated in accordance with this character. Such a character will eifect release Aof one or more of the reading relays 39 whereupon the circuit through the outer tongues and front contacts of relays 33a, b, c and e will be interrupted to open the circuit through relays 4| and 42. Each message transmitted from the line-transmitter 29 is terminated by an end-of-message signal and in the system to which4 the present invention is applicable, the end-of-message signal comprises two periods in consecutive order with no character except possibly a blank between the two periods.

When the end-of-message signal is being transmitted from the line transmitter 2li, the irst period in being stepped into and out of `the transmitter eiects operation of relays 4| and 42 in the manner set forth. If such a period is the rst of` an end-'of-message signal and no character, with the exception of a blank, intervenes between this period and a second period, the setting ofthe tongue of transmitter 20 in accordance with the second period again operates certain of the relays 39 so that the described circuit including the outer tongues of these relays, the second t0 fth tongues and back contacts of relay 43, through the coil of relay 31 to positive potential is completed. This circuit again operates relay 31 and the above circuit is extended through the tongue and front contact of relay 42, the outer tongue and back contact of relay 41, and through the coil of relay 48 to positive potential. Relay 48 thereupon operates and applies ground through its left hand tongue and front contact, through the coil 0f relay 44 to positive potential whereupon relay 44 is energized.

Normally, each time the brushes 49 of the multiplex distributor 32 contact segment 5| of the local ring, a positive step pulse is transmitted over conductor I0 of cable 52, through both coils of a differential relay 54,back contact and left handgtongueof relay 28, both coils of` differenv2,51 ness tial relay 36, and the' step magnet 56 of the line transmitter 25 to ground. Thus the tape transmitter under normal conditions is stepped for each revolution of the multiplex distributor brushes. When the plug 26- is inserted in a jack such as the W jack of the X turret, a parallel circuit for the step pulse after passing through both coils of diierentially Wound relay 54 is extended through contacts No. 9 of the plug 26 and jack W to the middle tongue of relay 44. Accordingly the operation of relay 4i extends the step pulse circuit from the front contact of the center tongue of relay 44 through the normally closed contacts 51 of relay 46 and the coil of a relay 58 to ground. Relay 44 in operating establishes a locking circuit for itself which in-V cludes its front contact and inner tongue, the back contact and left hand tongue of a relay 59 and the third tongue and front contact of relay 29.

With the step pulse circuit completed through the coil of relay 58, the next step pulse which is the one that will step the second period out of the line transmitter 2U also effects energization of relay 58. Operation of relay 58 extends the ground on the outer tongue thereof through the coil of relay 56 t0 positive potential. Relay 46 thereupon becomes energized and locks up through the front contact of the first tongue thereof. Relay 46 in operating also completes a circuit from positive potential through the coil of a relay 6I, front contact and outer tongue of relay d6, back contact and inner tongue of relay 41, and the third tongue and back contact of relay 59 to ground, whereupon relay 6I becomes energized. Operation of relay 6! through its first ve right hand tongues and associated front contacts connects the tongues of the X tape transmitter 21 through contacts 4 t0 8 of the plug and jack to the transmitting segments numbered l to of the multiplex distributor 32.

When relay 45 operates, a circuit is also completed from ground through the outer tongue and back contact of relay 59, the third tongue and front contact of relay 56,- and the left hand coil of relay 28 to the circuit including the No. 1 contact of the plug and jack and the coil of relay 28 to negative potential. This circuit shunts the resistance 3l whereupon the current through relay 26 is sulicient to cause its operation. When relay 28 operates, the-individual circuits normally extending from the rtongues of the line tape transmitterZll to the transmitting segments l to 5 of the multiplex distributor 32 are interrupted.

When the X turret plug 26 is inserted in an associated jack assigned to an outgoing circuit, the second and third contacts of the plug and jack extend the marking and spacing potentials from the multiplex distributor to the sixth and seventh tongues'of relay 6l. If the plug is inserted in a jack assigned to an A channel, the marking potential will be negative and the spacing positive, and at the associated jack circuit these potentials are normally connected through the sixth and seventh tongues of a yrelay `28 and associated back contacts to the 'spacing and marking bus bars of the associated line transmitter such as 2i).

When relay Bl operates in the manner deL scribed, the multiplex marking and spacing potentials are applied through front contacts of the sixth and seventh tongues of relay 6I to the marking and spacing bus bars of the X turret transmitter 21. The marking potential is applied directly fom the sixth tongue ofrela'y '6| to thema'rking bu'sv barwhile thefspacing potential from theVv seventh 'tongue of relay 6I extends tlirouglithe'inner `'tongue and back contact of relay 'lltl and the outer tongue vand back contact of 'arelay 62 to the spacing bus bar `of the X transmitter 21. Relays 28 zand 6l operate substantially together and-as relay 28 operates its sixth Iand seventh tongues removes the marking and spacing potential from the bus bars of the line transmitter 2B. Since these two relays operate When the left hand brush E9 of the multiplex distributor 32 is contacting segment 5l or at some time other than When the right hand or sending brush 59 is contacting the transmitting segments l to 5 of the transmitting ring, there is no interruption or` mutilation of a code group transmitted by the multiplex distributor.

Operation of relay 6I at its left hand tongue interrupts a circuit heretofore extending to a lamp 65. The circuit to the lamp 65 before operation of relay 6l' extended through the lamp, back contacts and tongues of relays 59 and 6I, to ground Aat the front contact and inner tongue of relay 29. As set forth, relay 29 was operated at the beginningof the sequence of operation to complete the circuit to the lamp 65. The illumination of lamp 62 indicates to the operator that the associated X turret transmitter 21 has been connected to an operative multiplex channel and, should the channel be busy, that the associated reading device will immediately commence reading the characters being transmitted over the multiplex channel and connect the X tape transmitter 21 thereto when the end-of message signal of the message, then in progress of transmission, reaches the line transmitter 2U. When lamp 65 ceases to be illuminated, which occurs o'n the operation of relay 6I, it indicates to the X turret operator that the X transmitter 21 is operatively connected to the multiplex distributor for transmission of a message thereto. When relay 28 operates, it opens the step pulse circuit normally extending through the back contact and left hand tongue thereof to the step magnet 56 of the line transmitter 20. Accordingly, the line transmitter 2U- does not stay locked down but the pins thereof are permitted to sense the next character in the tape following the second period of the transmitted end-ofmessage signal of the last message transmitted therefrom.

If the line transmitter 20 should happen to be idle when an X transmitter, such as 21, is connected to the associated multiplex channel, means are provided whereby after a predetermined length of time the X transmitter will be connected to the multiplex channel. When a line transmitter connected to a multiplex channel is idle, blank code combinations are transmitted over the associated channel and this condition exists whether or not the line transmitter is idle due to having no further messages to transmit or because the tape lever is operated due to taut tape. The tape may be taut to cause the transmission of blanks during the transmission of a message or beforek a complete message has been transmitted and it is normally undesirable to connect the X message transmitter to the multiplex channel at such a time.

Assume that the line transmitter 20 associated with the A channel of a multiplex has completed the transmission of a message in its control tape 2| and for the time being there are no more messages stored therein. As is the usual arrangement, the-perforator I8 will 'perforate sufcient blank tape to advance the last message character or the end-of-message signal of such a message over the pins of the transmitter and shortly thereafter the tape 2l will become taut and cause the tape lever contacts 1| to open. With the contacts 1l open, the next step pulse from the local ring of the multiplex distributor will pass through only the left hand coil of relay 36 and cause the operation thereof. The relay 36 is locked operated by a circuit from positive potential through the left hand coil of a relay 12, the left hand tongue and front contact and coil of relay 36, and the coil of the step magnet 56 of transmitter1 20 to ground. With step magnet 56 operated by the above circuit, the tongues thereof are locked against the spacing bus bar and this condition will exist until more tape is perforated by the perforator I8 to permit the tape lever contact 1I to close. With the tongues of tape transmitter 2U locked against the spacing bus bar, a blank code combination is transmitted over the associated multiplex channel for each revolution of the brushes. With the above assumed condition, the intra-cnice circuit |'9 is at this time also idle and during such a condition relay 13 will be unoperated. Relay 13 is operated when the associated intra-office circuit is busy and although the circuits for operating this relay are not shown in the drawings, it may be operated in the manner relay 81, Fig. 3 of Patent No. 2,279,295, is operated. Relay 12 operates in series with relay 36 and if at the time of operation thereof, relay 13 is unoperated, relay 14 will be operated through an obvious circuit. Relay 14 remains locked up as long as relay 13 remains in an unoperated condition.

The seventh conductor of cable 52 at the jack circuit is normally connected through the tongue and back contact of relay 14 to the fourth tongue of the line transmitter 20, and as heretofore described permits an X cord circuit when plugged up to the associated jack to determine the character of the fourth pulse oi eachcode combination transmitted from the busy line transmitter. For the above assumed conditions of an idle line transmitter 20 blanks are being transmitted to' the outgoing mutliplex channel and with relay 14 operated during the time a connection from the seventh conductor of cable 52 through a tongue and make contact of relays 36, 14 to the marking bus bar M of line transmitter 20 is established.

With the jack circuit in this condition, the plugging of an X plug 26 into an X turret jack such as the one shown in Fig. 2 will permit the reading device of the cord circuit to function as if a period were being transmitted from the associated line transmitter 20 even though the associated multiplex is transmitting blanks. For the above condition relays 39a, b, c and e will be operated while relay 39d will not'be operated. The operation of relays 39 in such a combination as pointed out completes a circuit through the coil of relay 31.` Relay 31 thereupon becomes operated and at its right hand tongue removes the negative potential normally applied through the second right hand tongue and back contact of relay 62 to the control grid of a vacuum tube 16. Negative potential on the grid of vacuum tube 16 normally keeps the same from passing cur- I rent and a predetermined length of time after the removal of the negative potential therefrom it will pass current. A grid leak device 11 consisting of a resistance and condenser determines the timelag between the removal of the negative l v10 potentialf fromthe'grid circuit andthe passing of `currentfthroughl vacuum tube 16. When vacuum tube 16 passes current, a circuit is com'- pleted from the plate thereof through the fourth right hand tongue of relay 59 and vthe* coil of relay 44 to positive potential. This circuit efl.- fects operation of relay 44 which' locks up through its first right hand tongue and a backcontact of relay 59 and a make contact of relay 23 to ground'. The operation of relay 44 in the manner set forth above extends the step pulse circuit to relay 58 to cause operation' thereof which in turn effects operation of relay 46. Relay 46 in turn effects operation ofrelays`28 and6l to transfer the control of the multiplex distributor from the line transmitterr20 to thefX transmitter 21. Thus when the line transmitter is'idle, a condition is set up whereby a period'is read in the connected X cord circuit reading device and if this condition prevails for a'predetermined length of time, as determined by thegrid leak 11, the transfer of the X transmitter to the sending circuit is effected. i

When an X transmitter such as 21 is connected to a sending circuit such as the A channel of a multiplex circuit, the reading device including the vacuum tubes 34 and relays 39 read each character transmitted from the X transmitter in the same manner as it reads characters transmitted from a busy line transmitter 20. Each X message is terminated by an end-ofmessage signal consisting of two periods and as the rst one of these is stepped over the pins of the X transmitter, relay 4| is operated in conjunction with the operation of relay 31. As the rst period in the tape is stepped out of the X transmitter relay 42 operates. The second period being stepped over the pins of the X transmitter effects operation of relay 48 which in turn completes a circuit vfor the operation of relay 41. Relay 41 in operating by its second tongue and front contact completes a circuit from ground through the coil of relay 59 to positive potential. Relay 59 thereupon operates and locks up through a front contact and its left hand tongue and also opens .the operating circuit to relays 28 and 6l. Relays 28 and 6| thereupon release and transfer the tongues of the transmitter 20 back to associated sending segments of the multiplex distributor 32 and remove the tongues of the X transmitter therefrom.

The operation of relay 59 also completes a circuit through the front contact and first right hand tongue thereof to cause illumination of a lamp 11. The illumination of lamp 11 indicates to the X turret operator that the transmission of the X message is complete and that the associated plug 26 may beremoved from the jack. On the removal of the plug 26 from the jack, the circuit to relay 29 is interrupted which in turn on releasing interrupts the circuits to relays 46 and 59 whereby said relays vand the associated cord circuit return to their normal condition.

If while the X tape transmitter 21 is transmitting to a sendingr circuit and its associated tape lever is operated to open its contacts 18, the next step pulse from the distributorwill pass only through the left hand coil rof the autocontrol relay 19 of the X cord circuit to cause operation'thereof. When the tape V241is not taut, the step pulses pass through both coils of relay 19 and have no effect thereon, and continue to yground through the step magnetvl of the X transmitter 21. When relay 19 operates, the first left hand `tongue thereof4 establishes a locking ,11. circuit therethrough 4from positive vpotentiatat the' back contact and left hand tongue; of :relay 62, the left hand coil; of relay 19, throughthe step magnet 8|A to ground. The tongues ofthe transmitter 21 .are held against their spacing-bus bar when the step magnet 8| is energized and therefore for this condition all-spacing code combinations are transmitted to the sending circuit. The next step Vpulse after the closingof the Ytape lever contacts I8 .due tol morel tape accumulating thereat eiiects release of1 relay 119: and step magnet 8| so that the ,tongues'of transmitterlmay be positioned in accordance with the character over the pins in the X tape transmitterand the transmission of message `characters resumed."

The operation of a .pull .tape key 82 during the time that the X cordY circuit is plugged upnhas they same effect as; opening the tape lever 'contacts 18 andV permits adjustment: of. the tape therein should suchbe desired. Operation oi key 82 when the X cord circuit is not'xplugged; up effects energization of thestepy magnet 8|y tbya circuit through back contacts of relays162- and -IIS.

Undery some conditions itmay be undesirable to wait' for the line transmitter such as 2114r to complete the transmission:` of a message -that is being. transmittedy before connectingfthe Xtape transmitter 21- to the sending. circuit. If such is the casev a so-called pre-erupt key 83; inv the X cord.y cincuitzmay-be operated whereby the X tape transmitter is immediately connected' tothe transmitting line orl channel.'Y Operation of/key 83 applies ground through the back'ccntact and fourth tongue of relay 59 and the coil of` relay 44 topositive potential', thereby effecting oper'- ation of relay'44. Assetforth, operationoirelay 44 conditioned the circuits to connect theI X transmitter to the sending circuit anddisconnect the line transmitter; therefrom. The, pre-empt key 8.3 is,xof course; operated after the plug 26 is inserted; inv the jackzandf whenoperated the connection of the X." transmitter to the sending,v circuit is effected without waitingL foran endof-message signal'to be readI in thereading.. device or thedelay provided: bythe vacuum tube.1.6.'

In the above description itwas assumed that the X cord circuit was plugged up to. a jack associated with an A channel of'a multiplex. .circuit .wherein markingl and-spacingV conditions lWere characterized bynegative and positive potentials, respectively. On a Blchannel of a multiplex circuit, as indicated at the: distributor |32, Fig.. 5, the marking and spacing conditions arepositiye and negativepotent-ials, respectively, andthe operation of the X cord circuit in. some respects isdiierent When plugged up toa BschannelIthan when plugged up`4 to an A` channel. In afja'cli. associated'with a B` channel, conductorsvZ1 and 3 from the multiplex distributor |32 have positive and negative potentialsfthereon. The extension of conductor 3l to. ani X cordA circuit-. establishesa leak circuit tothe grid of a vacuum tube 84fandf whenpluggedup to anA circuit, negative potential; onconductor 3 maintains vacuum tube lildunconducting Whereas ythe'positi've potential when plugged uptoa B channel renders tube 84v conducting. Relay 43 in the plate circuit of tube 84 therefore `is energized when the X cord circuitv is plugged! up to a B channel"y and deengized when the X cord circuit is pluggedi up to an Achannel;

The operation ofrelay 43'fconnects the front contactof Athe seventh-tongueA of relay 6| through the-,first tongue and frontzoontact of. relay'43 to thespacing bus: bar. of: the X transmitter 21 soy thatV when relay 6| subsequently operates, negative Vpotential will be applied to the spacing bus bar. Thepositive marking potential from the distributor |32 extends through the No. 3 contacts of the plug and jack 26 to the sixth tongue .of relay 6|, the front contact of which is connected to the marking bus bar lVl of the X transmitter 21.

The operation of relay 43 also through its second to sixth tongues reverses the circuits asso'- ciated with ythe front and back contacts of the outer tongues of relays 30. inv such a manner that when these relays are operated in accordance with a period code combination being transmitted over the B channel, a circuit will be completed to eiect operation ofV relay 31. For this condition, only relay 39d will be operated while the other relays 39a, b, c and e will be unoperated. If a second period follows the rst, the X" transmitter is'switched to the sending circuit and thepreviously connected line transmitter disconnected therefrom in the manner pointed out above. Thusthe reading device including the relays 3S and vacuum tubes 34 are adapted to read the characters being transmitted over either an A or B multiplex channel and to switch the X tape transmitter into the circuit when an end-of-message signal is detected in either ci such types of circuits. In all other respects, the X cord circuit operates` in substantially the saine manner when connected to a B channel as when connected to an A channel.

Fig. 5 shows the essential circuits of a jack circuit connectionthat may be assigned toa teleprinter line suchasthat represented as leading to orifice Z. Here'the tongues of line transmitter |20 are normally associated With the teleprinter sending line through back contacts and tongues of a relay |28. The code combinations transmitted from the line transmitter |20 are distributed to the sending circuit through the operation of a constantly rotating distributor |30.

When the plug 26 of the X cord circuit is inserted in the jack such as the Z, Fig. 5, associated lwith the teleprinter line extending to remote oice Z, relay 29 of the cord circuit operates by a circuit extending through the No. l contacts of the plug and jack and the coil of relay |28 to positive potential. Relay |28, however, does not operate at this time since resistance 3| limits the current to some value below that necessary to operate relay |28. A leak circuit iromthe-No. 1 contact of' plug 26 extends through a resistance 86. to the control grid of a vacuum tube 81. When plugged up to a teleprinter jack, theNo. 1 contact of plug 26is connected-to positive potential and thepositive potential applied to the grid of vacuumv tube 81 permitsthe same to pass current. They coil of relay 62is inthe plate circuit of vacuum tubef 81 and; therefore, relay |52v becomes operated at-this time. Relay 62' locks up through itsfirst tonguev andthe front contact and second tongue of relay 29to ground.

The spacing impulses transmitted over a teleprinter line are normally intervals of no current whereas the marking impulses are normally intervals of either positive or negative potentials. In the jack circuit shown in Fig. 5 for the teleprinter line to oflice Z the marking impulses are intervals of negative potential. On the plugging operation, the reading device of the X cord circuit' begins toread the characters transmitted from the line transmitter |20 if the same is active andthe grids of vacuum tubes 34 will have substantially zero. potential or negativepotential applied thereto in accordance with the spacing and marking impulses transmitted from the transmitter |20. Vacuum tubes 34 pass current when the grids are positive or have substantially zero potential thereon and, accordingly, when a period from a teleprinter line transmitter such as |20 is read, only the fourth tube 34 will not pass current and all relays 39 except 39d will be operated. This condition as described effects operation of relay 31 which is followed by operation of relay 4| and if'a second period follows immediately, or without othercharacters being interposed between thev two periods, relay 44 is operated to initiate the sequence of operation whereby relays |20 and 3| areloperated to connect the X transmitter to the sending circuit and disconnect the line transmitter |20 therefrom.

During an idle condition of a teleprinter line such as that extending to oice Z, Fig. 5, marking potential is applied thereto. If this condition is caused by taut tape opening the tape lever contacts 1| associated with the teleprinter line transmitter |20, the auto-control relay |30 will be in an energized condition and if the taut tape is due to the associated intra-oiice circuit |9 being idle, the relay |13 will be unoperated. Accordingly, when relay |36 operates, relay |12 will for such acondition also operate and be locked up by a circuit through the right hand winding thereof and the coil of relay |14. Thus relay |14 will also be operated and remain locked up during such an'idle condition of the teleprinter transmitter |20. Operation of relay |30 effects energization of the teleprinter transmitter stepping magnet |56 and the locking of the tongues thereof against the spacing bus bar. With the relays |35 and |14 operated, steady negative marking potential from the rest segment |15 of the distributor E30 is appli-ed through the seventh tongue and back contact of relay |28, the second right hand tongue and front contact of relay |30, the No. 2 conductor of cable |52, to the solid ring |3| of theldistributor |30 and to the outgoing teleprinter line to olice Z. This marking potential is also` applied through the sixth tongue and back contact of relay |28, the iirst right hand tongue and front contact of relay |36, the tongue and front Contact of re# lay |14, to the spacing bus bar of transmitter |20. Thus as the right hand brush of distributor 30 wipes over the transmitting segments 1 to 5, marking potential is applied through contacts Nos. 4 to 8 of the plug and jack to the grids of vacuum tubes 34. This negative potential maintains the tubes 34 non-conducting and their associated relays 39 in a deenergized condition.

The operation of relay 02 incidentr to the plugging operation, by means of its second right hand tongue connects thegrid of tube 16 to the front contacts of the inner tongues of relays 39. These tongues of relaysv 39 are connected through the back contact and right hand tongue of relay 31 to negative potential so that the operation of any one of these relays maintainsthe control grid of vacuum tube 10 in a negative condition. However, as set` forth, relays 39 are all deenergized during an idlecondition ofthe teleprinter line transmitter Y |20 and therefore the operation of rel-ay 62 permits vacuum'tube 10 to become conducting for such a condition after the operation ofrelay 02 and the dissipation of the negative charge on the grid through the grid leak ||1. When tube 10 passes cur.- rent, it causes operation of relay 44 Ato initiate 14 the sequence of operation whereby the X transmitter 29 is connected to the sending circuit and the teleprinter transmitter |20 disconnected therefrom. r.TJ-his operation consists primarily of energization ofv relays 6| and |28.

Operation of relay 62 by its left hand tongue applies neg-ative potential to the rst left hand tongue of relay 19 so that should relay 19 operate, as a result of taut tape between the printer-perforator 23 and the"X transmitter 21 causing the opening of tape lever contacts 18, negative potential is applied through the step magnet 8| to ground. Operation of relay 19 establishes a circuit for the negative marking potential brought into the X cord circuit through .contact No. 3 of plug 26 and the sixth tongue and front contact of relay 0| which will be operated at this time, through the front contact and right hand tongue of relay 19, the front contact and outer right hand tongue of relay 62, the back contact and first tongue of relay 43, the front contact and seventh tongue of relay 6I, through the No. 2 contact of plug 26 and teleprinter jack to the solid ring |3| of distributor |30 therein. In this manner taut tape inthe X transmitter |21 when connected to and transmitting over a teleprinter linecauses marking potential to be applied to the line.

If the X transmitter 21 is plugged up to a teleprinter line that is idle because the tape lever contacts |1| associated with the line transmitter are open while the associated intra-oice I9 is busy, the X transmitter vvvillnot at this time, withoutoperation of thefpre-empt key 83, be operatively connected to the teleprinter line. As pointed out, steady marking potential is applied to the teleprinter line through the outer tongue and front contact of relay |30 when the tape lever contacts |1| are open, and if at this time the intra-oce circuit |9 is busy,as indicated by the energized condition of relay |13, relay |14 will not be operated. Accordingly, steady negative potential will not be applied to the spacing bus bar S against whichv the tongues of the line transmitter |20 are locked as is the case if the tape lever contacts |1| are open during the time the intra-ofce circuit I9 is idle.

With the spacing bus bar S open, no potential will be applied to the grids of tubes 34 and they will pass current to operate all the associated relays 39 only while the teleprinter distributor brush is passing over segments |15 and S of the transmitting ring. While the brush is passing over transmitting segments 1 to 5, negative potential from the segment |15 will be applied through the tonguesof transmitter |20 and the spacing bus bar `Sto the grids of tubes 34 and cause deenergization of the relays 39. This sequence will be repeated for every revolution of the distributor brushes and the periodic application of negative potential to the grid of tube 16 through theinner tongues and back contacts of relays 39 will for these conditions prevent the same from passing current to operate relay 44 and initiate the vSequence of operation that would transfer the;control of the distributor |20 to the X transmitter from the regular line transmitter |20.

In substantially all other respects the Xl cord circuit and teleprinter jack circuit operate in m'uchxthe same manner as that described above in connection with theftransmission to multiplex circuits. The operation of thepre-empt key 83 ofvthefX cordl circuit immediately connects the X transmitter to a teleprinter line regardless of the busy or idle condition' thereof.

While the foregoing is a detailed description of one form of the invention, it is obvious that various modifications thereof may be made if desired without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. In a telegraph switching system, a plurality of sending circuits i'lrst transmitters normally operatively associated with said circuits for transmission thereover, a second transmitter, a reading device associated with said second transmitter, manually operable means for. unoperatively associating said second transmitter with any one of said sending circuits atA a time and incident thereto render said reading/device operl ative to read signals transmitted from a rst transmitter and means controlled by said reading device on the detection of certain signals. transmitted rom said first transmitter to-said sending circuit or the absence of signals from said first transmitter to operatively disassociate said-first transmitter from said sending circuit and'operatively associate said second transmitter therewith,

2. In a telegraph-switching system, a plurality of transmitting circuits, a plurality of irst and a single second storage controlled transmitting means, said first transmitting meansbeing normally conditioned to transmit to said transmitting circuits signals stored in associated storage medium, a signal reading means, manually operable-means to associate said reading means with any one of said transmitting circuitsto read the signals transmitted thereover and to condition said second transmitting means for connection to said transmitting circuit for transmission thereover of signals stored in its associated storage medium, means controlled by said signal reading means in response to an -end-of-message signal transmitted from said rst transmitting means to stop further transmission from said first transmitting means and initiate transmission from said second transmitting means to said transmitting circuit.

3. In a telegraph switching system, a plurality of transmitting circuits, a plurality of first storage controlled transmitting means normally con ditioned to transmit to associated transmitting circuits signals stored in their associated storage medium, a second storage controlledtransmitting means, a signal reading means, manually operable means to associate said reading means with said transmitting circuits to read the signals transmitted thereover and to condition said second transmitting means for connection to a transmitting circuit for transmission thereover of signals stored inits associated storage medium,` means controlled by said signal readingmeans in response to an end-of-message signal transmitted from said rst transmitting means to stop further transmission from said first transmitting means and initiate transmission from said second transmitting means to said transmitting circuit, and means controlled by said signal reading means in response to an end-of-message signal transmitted from said second transmitting means to stop further transmission therefrom andi reconnect said rst transmitting means to saidtransmitting circuit. y'

4. In a telegraph switching system,` a plurality of sending circuits, a transmitter individual to and adapted to transmit signaleode` groups of marking and spacing linek conditions over associated sending circuits with the marking and spacing lineY conditions on onefsendingL circuit corresponding to the spacing and marking line conditions on another sending circuit, an auxiliary transmitter normally disassociated from all of said sending circuits, signal reading means associated with said auxiliary transmitter, means for connecting said reading means to any of said sending circuits to read signal code groups, if any, transmitted from associated transmitters, means for automatically connecting said auxiliary transmitterto such a sending circuit in response to an end-of-message signal from its normally connected transmitter and means for automatically adapting said auxiliary transmitter to transmit the proper line conditions to its connected circuit representative of the signals stored in its control medium.

5. In a telegraph switching system, a plurality of different types of sending circuits wherein marking and spacing code group signal impulses are represented by different line conditions on different types of said circuits, individual line transmitters normally associated with said circuits for the transmission thereover of signals stored in associated storage means, an auxiliary transmitter, a signal reading device associated therewith, means for associating said reading dcvice with said sending' circuit one circuit at a time, means for'conditioning said reading device in accordance with the circuit to which it is associated to properly read marking and spacing impulses transmitted thereover and'means controlled by said reading device on the reading of predetermined code groups to disconnect the line transmitter from the sending circuit, connect said auxiliary transmitter thereto and adapt said auxiliary transmitter to transmit marking and spacing impulses to the circuit representative of its storage means in accordance with the type of circuit.

6. In a telegraph exchange system, a plurality of diierent types of sending circuits, a sending signal distributor means individual to each of said circuits, a transmitter and associated signal storage medium individual to each cf said distributors and normally arranged to control the same to transmit code groups of line conditions characteristic of its line in accordance with the signals stored in its storage medium, an auxiliary transmitter, a signal reading device, means for associating said reading device with said sending circuits. one at a time, means for adapting said reading device to determine the type of circuit with which it is associated and control said device in accordance therewith, means controlled vby said reading device to associate said auxiliary transmitter with the circuit it is reading on the detection of predetermined code groups and adapt said auxiliary transmitter to control the associated distributor to transmit to said circuit code groups of line conditions characteristic thereof in accordance with the signals stored in the storage medium of said auxiliary transmitter.

7. In a telegraph switching system, a plurality of different types of sending circuits wherein marking and spacing code groupsignal impulses are represented by different line conditions on diierent types of said circuits, individual primary transmitting means normally operative to eiect transmission of signal code groups over associated sending circuits, a secondary transmitting means, means for associating said secondary transmitting means with any one of said sending circuits at a time and means associated with said secondary transmitting means to determine the type. of sending circuit to: which` it is associated and adapt the same to transmit code groups of impulses thereover in accordance with its associated storage medium whereby character representing signal impulses transmitted from said secondary transmitting means are the same as signal impulses representing similar characters transmitted from the primary transmitting means of the circuit to which said secondary transmitting means is associated.

8. In a telegraph system, a plurality of local transmission circuits, storage medium preparing devices controlled by signals received over said circuits to store the received signals in associated mediums, signal sending circuits, rst transmitters controlled by associated mediums to transmit stored signals to said sending circuits, a second transmitter, means for establishing a partial connection between said second transmitter and any one of said sending circuits and if its first transmitter is busy to read the signal being transmitted, means to complete the connection of said second transmitter to said circuit on the transmission of an end-of-message signal from its rst transmitter, and means operative on the establishment of a partial connection and the detection of an idle condition of an associated irst transmitter to determine the condition of said local circuit and to complete said connection on the detection of an idle rst transmitter and an idle local circuit.

9. In a telegraph system, a local transmission circuit, a, storage medium preparing device controlled by signals received over said circuit to store the received signals in a medium, a signal sending circuit, a rst transmitter controlled by said medium to transmit stored signals to said sending circuit, a second transmitter, means for establishing a partial connection between said second transmitter and said sending circuit and if said rst transmitter is busy to read the signal being transmitted, means to complete the connection of said second transmitter to said circuit on the transmission of an end-of-message signal from said first transmitter, a timing means, and means controlled by said timing means and operative on the establishment of said partial connection and the detection of an idle condition of said local circuit to complete said connection after a predetermined length of time after the detection of an idle rst transmitter and an idle local circuit.

10. In a telegraph system, a sending circuit, a rst transmitter normally operatively associated with said circuit, a second transmitter, a rst manually operable means for initiating the disassociation of said rst transmitter from said circuit and the assication of said second transmitteer therewith, means to normally delay full operation of said means when said iirst transmitter is busy until the transmission of an endof-message thereby and a second manually operable means for effecting full operation of said means substantially immediately after operation of said rst manual means.

ll. In a, telegraph system, a sending circuit. a first transmitter normally operatively associated with said circuit, a second transmitter, switching means including a plug and jack for associating a second transmitter with said circuit, means normally operative on the insertion of said plug in said jack to switch control of said circuit from said first transmitter to said second transmitter following the transmission of predetermined signals from said rst transmitter and means to effect said switching operation substantially immediately on said pluggingoperation.

12. In a telegraph system, a sending circuit, a first transmitter normally operatively associated with said circuit, a second transmitter, switching means including a plug and jack for associating said second transmitter with said circuit, means normally loperative on the insertion of said plug in said jack to switch control of said circuit from said first transmitter to said second transmitter following the transmission of predetermined signals from said first transmitter, means to eiect said switching operation substantially immediately on said plugging operation, and means operative with said second transmitter in control of said circuit to switch control thereof back to said first transmitter on the transmission of predetermined signals from said second transmitter.

13. In a telegraph system, a plurality of telegraph channels of communication adapted to have character code groups of impulses of different line conditions transmitted thereover with the same characters represented by different line conditions on diierent channels, a character reading device and a storage controlled transmitter associatable with said diierent channels one at a time, a control circuit operated by said reading device and means controlled by said reading device to operate said control circuit to condition said transmitter to transmit to the associated channel code groups representative of stored characters on the reading of a predetermined character transmitted over any one of said circuits with which it is associated.

EDWARD J. AGNEW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,943,475 Gurley Jan. 16, 1934 2,193,809 Dirkes Mar. 1 9, 1940 2,340,576 Bacon Feb. 1, 1944 2,379,865 Connery July 10, 1945 2,406,787 Bacon Sept. 3, 1946 

